Management systems which use a computer for monitoring, controlling and reporting on the status of a piece of process equipment in a manufacturing facility are generally known in the art and have been in existence for several years. In the semiconductor manufacturing industry, for example, gas cabinets are used to supply high purity process gases used in wafer fabrication. The various process gases contained in these gas cabinets are highly toxic. Accordingly, it is critical to be able to closely and safely control the flow of gases through the gas cabinets to ensure the health and safety of the workers. Also, it is very important to know up to the minute information regarding the status of each gas cylinder within each cabinet in order to ensure smooth and timely switchovers when the gas cylinders become empty and therefore avoid "dry runs" or other misprocessing errors.
Typically, in the known gas management systems, each gas cabinet includes a programmable logic controller (PLC) which communicates status and alarm information to a mainframe or minicomputer. Each PLC monitors several internal inputs (such as gas applied pressure, gas delivery pressure, flow rate, etc.) as well as several external inputs (such as toxic gas detectors, UV/IR sensors, seismic sensors and the like). Until recently, these mainframe and minicomputer-based systems provided the only solution for computerized gas management on a facility-wide scale since only these systems could provide the necessary memory and performance to archive and save changes and alarms.
However, the information fields displayable on a host terminal in these systems were very primitive. Also, the software written for these systems were not capable of being programmed to perform more than a limited number of tasks. Further, these systems were cost prohibitive to many users.
Over the last three years, there has been a major shift in the technology such that personal computers (PCs) now approach the speed and performance levels previously only attainable by mainframe or minicomputer based systems. As the PC became more powerful, many facility management software packages were developed to take advantage of the increased performance they offered, including providing graphic screen displays which contained some simple information concerning the gas cabinets. This, in turn, afforded the user some limited monitoring capability. As the software at the PC level became more robust, it also proved that it had the capability and safety to perform the desired control functions. Accordingly, it is now common to see more and more PC-based gas management and control packages which operate on a single stand alone device. These systems are fully functional in that they provide display of graphical depictions of a gas cabinet and usually also provide the functional capabilities for data acquisition, data logging and report generation and offer some control capability.
However, one of the problems in writing software for such PC-based systems is supporting changes in the graphics software and finding bugs in order to give the customer a graphical user interface (GUI) with the desired options. Consider, for example, the typical software problems encountered each time a user desires to upgrade or replace a peripheral piece of equipment within a system. Typically since in the usual case, each piece of peripheral equipment, whether it is a printer, a monitor, a keyboard, or a mouse, has its own dedicated hardware interface. Accordingly, for an upgrade, the controlling software has to be tied in some way to the new device interface. Where the upgradable device includes additional functions, such as video, voice, I/O control, etc., a higher level of software knowledge and technique is required in order to properly incorporate the new functions into the existing system. Also, since the graphic capabilities of a system take up approximately 80% of the software time and investment, response time between the data sources to be maintained and controlled and the controlling computer decreases significantly as additional data sources and/or I/O devices are added to the system.
Accordingly, there is a definite need in the art for a management system which permits the addition of a substantially unlimited number of data sources such as PLC operated gas cabinets and other process equipment, to be controlled by a host computer on a system without a significant decrease in response time. There is also a need in the art for such a system which permits the modular integration of existing software packages and hardware interfaces which use different protocols.
Accordingly, it is a principle object of the present invention to provide an improved management system for monitoring and control of a plurality of data sources in a facility which overcomes the problems of the prior art.
In particular, it is an object of the present invention to provide a facility and gas management system for real time data gathering, analysis and control of gas cabinets and related process equipment in a wafer fab facility.
It is another object of the present invention to provide a facility and gas management system which operates in a distributed processor environment including a host processor having graphic, control and user interfaces for operating in a work station environment and a multi-ported processor networked to the host processor and having commercially available hardware interfaces for communication with controllers for the gas cabinets and the other connected devices in their respective protocol specific PLC environments and wherein the multi-ported processor includes software means for emulating a common protocol such that each gas cabinet or other connected device appears to the host processor as an address location in a memory of the multi-ported processor and wherein the address locations are sequentially polled for updated status, alarm and set point information which is displayable to a user/operator at the host processor.
Other and further object will be apparent from the following written description, drawings and claims.